The purpose of this project is to study the nature of tumor antigens associated with cells tranformed by either SV40 virus, chemicals or spontaneous induction; and the relation of these antigens with gene expression and host immune mechanisms against these antigens. Current research is carried out on: 1) Study of the relationship between SV40 5, surface and tumor specific transplantation antigens, and their relationship to SV40 A gene expression; 2) Study of the host immune response against SV40 transformed cells; 3) Study of the immunogenicity of spontaneously transformed cells and of these cells super-infected by SV40; 4) Solubilization and characterization of common rat tumor cell antigen.